In the process of realizing the technical solution of the embodiment of the present application, there are at least the following technical problems in the related art:
with the rapid development of the Internet and the popularity of large-screen multi-function mobile phones, a large number of mobile data multimedia services and various high-bandwidth multimedia services, such as video conferencing, TV broadcasting, video on demand, advertising, online education and interactive games, have been emerged. These services, in one aspect, meet the growing service demands of mobile users, and also bring new business growth points for mobile operators in another aspect. These mobile data multimedia services require that multiple users can simultaneously receive the same data, which, compared with general data services, have features of a large amount of data, long duration, time-sensitive and so on.
In order to utilize the mobile network resources effectively, the 3rd Generation Partnership Project 3GPP proposes Multimedia Broadcast/Multicast Service MBMS. The MBMS is a technology transferring data from one data source to multiple targets, thus realizing the sharing of network resources (including core network and access network) and improving the utilization rate of network resources (especially air interface resources). MBMS defined by 3GPP not only can implement message-based multicast and broadcast with plain text and low-rate, but also can implement broadcast and multicast of high-speed multimedia services. The MBMS offers a wide variety of enriched videos, audios and multimedia services, which conforms to the trend of future mobile data development and provides a better business prospects for the 3G development.
In the Long Term Evolution LTE, the MBMS service may use the multicast mode, which is called Multicast/Broadcast over Single Frequency Network MBSFN transmission mode, and the MBMS service that uses the multicast mode is also called MBSFN service, which may use the same modulated coding format and the same physical resources to generate the same content in a plurality of cells. MBMS multi-cell transmission has the following features: 1) synchronous transmission in the MBSFN area; 2) support to combine multi-cell MBMS transmission; 3) Multicast Traffic Channel MTCH and Multicast Control CHannel MCCH are mapped to the MCH transmission channel under the point to multi-point p-T-m mode; 4) MBSFN-synchronized area, MBSNF area, MBSFN transmission, Advertisements and reserved cells are all semi-statically configured by the operation and maintenance. Therefore, user equipments UEs of the plurality of cells may receive a plurality of MBMS data having the same content and perform a single frequency network SFN combination, in order to increase the gain of the received signal. The multiple cells that use the same physical resources and use the MBSFN transmission mode to transmit the same MBMS service constitute one MBSFN area.
In an actual LTE networking, there are a plurality of MBSFN services in one MBSFN area. All MBSFN services belonging to the same MBSFN area are called an MBSFN service group. That is, one MBSFN service group only belongs to one MBSFN area. An MBSFN area includes a plurality of cells, each of which is configured with exactly the same MBSFN service group. The MTCHs with multiple MBSFN services of the same MBSFN area and the control channel MCCH of MBSFN services may be multiplexed into one Multicast CHannel MCH. The MCCH and a plurality of MTCHs, i.e., a plurality of logical channels, of the same MBSFN area may be mapped onto the same transmission channel MCH; the MCH is carried by the transport block of the MBSFN subframe.
In the existing art, the MSAP occasion is also introduced in an MBSFN Subframe Allocation Pattern MSAP concept. The MSAP occasion indicates all multicast resources included in one MCH corresponding to a certain MSAP in a time period of a dynamic scheduling period. A plurality of MTCHs and dynamic scheduling information may be transmitted in one MSAP occasion, and the MCCH is also included. The dynamic scheduling information is carried in a Media Access Control Protocol Data Unit Control Element MAC PDU CE, and the length of an MSAP occasion may be 320 ms. The time length of one MSAP occasion is a scheduling period, also known as a dynamic scheduling period. One MCH is allocated with one or more MBSFN subframes in one or more MBSFN frames through the MSAP, herein a subframe transmitted in the multicast mode is called an MBSFN subframe and a frame containing the MBSFN subframe is referred to as an MBSFN frame.
Each MSAP occasion configured on one MCH carries the dynamic scheduling information that carries mapping information of the MTCH to the secondary MSAP subframe. This mapping information is determined by means of the MBSFN subframe index-number relationship in one scheduling period. UE may know that each MTCH is allocated to which MBSFN subframes by reading the scheduling information, and the UE may read the MTCH which the UE is interested in on the corresponding MBSFN subframes and ignore the MBSFN subframes which the UE does not need to read, thereby improving the MBMS traffic reception efficiency of the UE and saving the power consumption of the UE. Here, the MBSFN subframe number is determined as: all the MBSFN subframes allocated by an MCH in a scheduling period are sequentially ordered and numbered.
In the existing LTE techniques, multiple logical channels multiplex the MCH channel through the following way: one subframe corresponds to one Transmission Time Interval TTI, one Transport Block TB may be transmitted in one TTI, and each TB corresponds to one Medium Access Control Protocol Data Unit MAC PDU. One MAC PDU may include a plurality of Service Data Units MAC SDUs. These MAC SDUs may be from different logical channels, and possible logical channels include MTCHs, MCCHs, and the like. The data from these different logical channels are concatenated together in the MAC PDU and then transmitted on the physical channel.
The MBMS Scheduling Information MSI MAC control unit, as shown in FIG. 1, is identified by an MAC PDU header carrying a Logical Channel Identifier LCD. The MAC control unit has a variable length of 2xbytes (x is the number of elements in the MBMS-SessionInfoList sequence). Each MTCH shall include the following fields:
LCID: this field indicates the logical channel ID of the MTCH, and the length of this field is 5 bits.
Stop MTCH: this field indicates the serial number of the corresponding MTCH end subframe in the MSAP occasion, and the length of this field is 11 bits. The specified Stop MTCH value 2047 indicates that the corresponding MTCH is not scheduled, and the values of the range 2043 to 2046 are reserved.
When a certain MTCH in the MAC PDU is not transmitted, 2047 is used to identify the Stop MTCH. The MCCH information includes the MCH in the MBSFN area, that is, resource configuration of the Physical Multicast CHannel PMCH, i.e., the subframe position information of the MCH, and Modulation and Coding Scheme MCS, MBSFN subframe allocation pattern, and so on. The UE obtains the corresponding MSI starting position through the MCH configuration information in the MCCH, in order to obtain the configuration information of the MBMS service which is interested by the UE. The MCCH periodic transmission includes the repetition period and the modification period. One modification period includes a plurality of repetition periods, and the MCCH content keeps unchanged, while the MCCH content may be changed in different modification periods. FIG. 2 shows a diagram of the MCCH modification period.
Cluster communication system is a specific wireless communication system developed to meet the command scheduling requirements of users in the industry and oriented for the specified applications in the industry. A large number of wireless users in the system share a small number of wireless channels. The cluster communication system takes command scheduling as the main application, and is a multi-purpose, high-efficient wireless communication system. Cluster communication system has a wide range of applications market, such as the government sector, public safety, emergency communications, electricity, civil aviation, petrochemical and military. In 3GPP LTE, cluster communication is called Group Communication Service Enabler GCSE.
The industry is currently discussing the possibility of using the MBMS technology to achieve cluster communications. The existing minimum MCCH modification period is 5.12 seconds, and the minimum MSP is 80 ms. In order to meet the delay requirements of the GCSE service, especially to speed up the session start process of the MBMS, it needs to consider shortening the minimum MCCH modification period and the minimum MSP. Considering the forward compatibility issue, the 3GPP R12 preliminarily determines to shorten the minimum MSP, but no agreement has been reached on shortening the minimum MCCH modification period, while the 3GPP R13 determines to shorten the minimum MCCH period.
If the 3GPP R12 does not shorten the MCCH minimum period and the R13 shortens the minimum MCCH period, the UE in the R12 may have the forward compatibility issue, which is mainly reflected in the impact on the MBMS traffic data update, and it needs to be configured on the network side to solve this forward compatibility issue. However, there is no solution to this problem in the related art.